Transmission rate control method, transmission rate control system, and mobile station

ABSTRACT

A transmission rate control method for controlling a transmission rate of a channel to which the transmission rate control method is applied, include: notifying, at a radio network controller, at a timing of a call setup or the like, a primary allowable transmission rate of the channel to which the transmission rate control method is applied; starting, at a mobile station, after the call setup, transmission at a transmission rate below the primary allowable transmission rate, when data to be transmitted is generated; and controlling, at the mobile station, the transmission rate of the channel to which the transmission rate control method is applied, based on an Absolute Grant Channel transmitted from a radio base station.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. P2005-082782, filed on Mar.22, 2005; the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transmission rate control method, atransmission rate control system, and a mobile station.

2. Description of the Related Art

In a conventional mobile communication system, in an uplink from amobile station UE to a radio base station Node B, a radio networkcontroller RNC is configured to determine a transmission rate of adedicated channel, in consideration of radio resources of the radio basestation Node B, an interference volume in an uplink, transmission powerof the mobile station UE, transmission processing performance of themobile station UE, a transmission rate required for an upperapplication, and the like, and to notify the determined transmissionrate of the dedicated channel by a message of a layer-3 (Radio ResourceControl Layer) to both of the mobile station UE and the radio basestation Node B.

Here, the radio network controller RNC is provided at an upper level ofthe radio base station Node B, and is an apparatus configured to controlthe radio base station Node B and the mobile station UE.

In general, data communications often cause burst traffic compared withvoice communications or TV communications. Therefore, it is preferablethat a transmission rate of a channel used for the data communicationsis changed fast.

However, as shown in FIG. 1, the radio network controller RNC integrallycontrols a plurality of radio base stations Node B in general.Therefore, in the conventional mobile communication system, there hasbeen a problem that it is difficult to perform fast control for changingof the transmission rate of channel (for example, per approximately 1through 100 ms), due to processing load, processing delay, or the like.

In addition, in the conventional mobile communication system, there hasbeen also a problem that costs for implementing an apparatus and foroperating a network are substantially increased even if the fast controlfor changing of the transmission rate of the channel can be performed.

Therefore, in the conventional mobile communication system, control forchanging of the transmission rate of the channel is generally performedon the order from a few hundred ms to a few seconds.

Accordingly, in the conventional mobile communication system, when burstdata is generated as shown in FIG. 2A, the data are transmitted byaccepting low-speed, high-delay, and low-transmission efficiency asshown in FIG. 2B, or, as shown in FIG. 2C, by reserving radio resourcesfor high-speed communications to accept that radio bandwidth resourcesin an unoccupied state and hardware resources in the radio base stationNode B are wasted.

It should be noted that both of the above-described radio bandwidthresources and hardware resources are applied to the vertical radioresources in FIGS. 2B and 2C.

Therefore, the 3rd Generation Partnership Project (3GPP) and the 3rdGeneration Partnership Project 2 (3GPP2), which are internationalstandardization organizations of the third generation mobilecommunication system, have discussed a method for controlling radioresources at high speed in a layer-1 and a media access control (MAC)sub-layer (a layer-2) between the radio base station Node B and themobile station UE, so as to utilize the radio resources effectively.Such discussions or discussed functions will be hereinafter referred toas “Enhanced Uplink (EUL)”.

As described in the Non-patent literature (3GPP TSG-RAN TS25.309v6.2.0), in the Enhanced Uplink (EUL), it is required to transmit ascheduling request (RR: Rate Request) to a radio base station, so as toreceive a scheduling grant signal (scheduling Grant) from the radio basestation, for a channel (EDCH) to which a transmission rate control isapplied. Here, the radio base station transmits the Scheduling Grant inresponse to the RR transmitted by EDCH.

In addition, performing a transmission based on a transmission ratewhich is defined per a logical channel, without using the. SchedulingGrant, can be implemented in Non-scheduled Transmission. However, thelogical channel, which is defined as Non-scheduled Transmission, can notcontrol the transmission rate using the Scheduling Grant.

Accordingly, as shown in FIG. 12, in the channel to which thetransmission rate control is applied, a transmission of data can bestarted after transmitting RR to the radio base station and receivingthe Absolute Grant channel (AGCH) as the Scheduling Grant from the radiobase station.

Referring to FIG. 3, the operation before starting transmission ofuplink user data in the Enhanced Uplink (EUL) will be described.

As shown in FIG. 3, at step (1), a mobile station UE transmits a callsetup request to a radio network controller RNC, in other words, themobile station UE calls.

At steps (2) to (6), the radio network controller RNC performs a callsetup processing with cooperating with the mobile station UE and a radiobase station Node B, in response to the call setup request.

At step (7), the mobile station UE transmits the above mentionedscheduling request (RR) when data to be transmitted is generated,receives an Absolute Grant Channel as the Scheduling Grant from theradio base station Node B, and starts transmission of uplink user datavia a user data channel (E-DPDCH) at a transmission determined based onthe received Absolute Grant Channel.

FIGS. 4 to 6 show a configuration of a radio communication function ofmobile station which is used for the Enhanced Uplink (EUL), FIGS. 7 to 9show a configuration of a radio base station which is used for theEnhanced Uplink (EUL), and FIG. 10 shows a configuration of a radionetwork controller which is used for the Enhanced Uplink (EUL).

In the radio communication function of mobile station, an E-TFCselecting section as shown in FIG. 6 is configured to control atransmission rate of uplink user data to be transmitted via an E-DPDCH,based on an Absolute Grant Channel (AGCH) as a Scheduling Granttransmitted from the radio base station.

Here, as shown in FIG. 13, the mobile station UE is configured toreceive the Absolute Grant Channel (AGCH) from a cell #21 whichfunctions as a serving cell of the mobile station UE, when performing asoft handover processing between a cell #13 in a radio base station NodeB #1 and the cell #21 in a radio base station Node B #2.

Generally, if not otherwise specified, a radio base station means a cellin the radio base station, in the field of the Enhanced Uplink (EUL).

In the radio base station, a scheduling section as shown in FIG. 9 isconfigured to determine and transmit an Absolute Grant Channel (AGCH)which is common in a cell or an Absolute Grant Channel (AGCH) which isdedicated to each serving mobile station.

Here, a serving mobile station for a specified cell is a mobile stationwhich serving cell is the cell.

Generally, if not otherwise specified, a transmission rate includes atransport block size and a transmission power ratio (a ratio of anE-DPDCH transmission power to a DPCCH transmission power), in the fieldof the Enhanced Uplink (EUL).

However, as described above, there has been a problem that when a datawhich is to be transmitted is generated, a mobile station can nottransmit data until receiving the Scheduling Grant, in the communicationusing the EUL.

Further, even if the transmission of data is implemented without usingthe Scheduling Grant, this has been a problem that the transmission ratecontrol can not performed in the Non-scheduled Transmission.

Furthermore, a delay for the transmission rate control occurs, whichleads to a deterioration of a channel quality.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made considering the problems, and itsobject is to start transmission of data instantaneously, to comply witha transmission rate control, and to reduce a delay due to thetransmission rate control when data to be transmitted is generated.

Specifically, in a channel (EDCH) to which a transmission rate controlmethod is applied, a radio network controller notifies, at the timing ofa call setup and the like, a primary allowable transmission rate of theEDCH.

After the call setup, a mobile station starts transmission of data belowthe primary allowable transmission rate, when data to be transmitted isgenerated.

Then, the mobile station controls the transmission rate of the EDCHbased on the Absolute Grant Channel (AGCH) from a radio base station.

A first aspect of the present invention is summarized as a transmissionrate control method for controlling the transmission rate of the EDCHincluding: notifying, at a radio network controller, a primary allowabletransmission rate of the EDCH at the timing of a call setup and thelike; starting, at a mobile station, transmission of data below theprimary allowable transmission rate, after the call setup, when data tobe transmitted is generated; and controlling, at the mobile station, thetransmission rate of the EDCH based on the Absolute Grant Channel (AGCH)from a radio base station.

A second aspect of the present invention is summarized as the abovemobile station, the above radio base station the above radio networkcontroller, and a transmission rate control.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a functional block diagram of transmission rate control systemaccording to an embodiment of the present invention.

FIGS. 2A to 2C are graphs illustrating transmission of data in a mobilestation according to the embodiment of the present invention.

FIG. 3 is a sequence diagram showing a transmission rate control methodaccording to the embodiment of the present invention.

FIG. 4 is a functional block diagram of a radio communication functionalunit in the mobile station of the transmission rate control methodaccording to the embodiment of the present invention.

FIG. 5 is a functional block diagram of a baseband signal processingsection in the mobile station of the transmission rate control methodaccording to the embodiment of the present invention.

FIG. 6 is a functional block diagram of a MAC-e processing section ofthe baseband signal processing section in the mobile station of thetransmission rate control method.

FIG. 7 is a functional block diagram of a radio base station of thetransmission rate control.

FIG. 8 is a functional block diagram of a baseband processing section inthe radio base station of the transmission rate control method accordingto the embodiment of the present invention.

FIG. 9 is a functional block diagram of a MAC-e processing section ofthe baseband signal processing section in the radio base station of thetransmission rate control method according to the embodiment of thepresent invention.

FIG. 10 is a functional block diagram of a radio network controller ofthe transmission rate control method according to the embodiment of thepresent invention.

FIG. 11 is a graph illustrating a transition of the EDCH of thetransmission rate control method according to the embodiment of thepresent invention.

FIG. 12 is a graph illustrating a transition of an uplink transmissionrate in the conventional transmission rate control method.

FIG. 13 is a graph illustrating a configuration of channels in theEnhanced Uplink (EUL).

DETAILED DESCRIPTION OF THE INVENTION Configuration of Transmission RateControl System According to First Embodiment of the Present Invention

Referring to drawings, an embodiment of the present invention will bedescribed. Here, in the drawings, the same or a similar reference signsare given to the same or similar portions of each drawing. In thisregard, care should be taken that these drawings are showing simplifiedformats of the present invention.

FIG. 3 is a sequence diagram showing the operations of the presentinvention. FIG. 3 shows an example of transmitting data at the mobilestation.

However, the example of receiving data at the mobile station is alsoincluded in the present invention.

In step (1), a mobile station requests, to a radio network controller, acommunication using EDCH.

The radio network controller admits a request from the mobile station,and requests a call setup for the EDCH to a radio base station which hasthe mobile station under the control.

If the call setup is implemented successfully, the radio base stationreports the result of the call setup to the radio network controller.

Then, in step (4), the radio network controller requests to the mobilestation a setup of control channel. Here, the control channel is usedfor signaling information on a type of the call, a release number of themobile station, a transmittable/receivable data rate and the like.

When the mobile station can setup the control channel based on therequest from the radio network controller, in step (5), the mobilestation reports the result of the setup to the radio network controller.

After the setup of the control channel, in step (7), various parametersrelating to EDCH (transmission amplification ratio in each format, orthe like) are signaled, so as to start a transmission of user data.

During this signaling, the radio network controller notifies a primaryallowable transmission rate for the mobile station.

After the E-DCH communication starts, when data to be transmitted isgenerated in the mobile station, the transmission of user data isperformed below the primary allowable transmission rate from the radionetwork controller, without using the Scheduling Grant from the radiobase station.

Further, when an AGCH from the radio base station is received, thetransmission rate shifts based on the AGCH.

FIG. 11 is a graph illustrating a transition of a rate of EDCH accordingto the embodiment of the present invention.

A mobile station is notified a primary allowable transmission rate (R₀)from a radio network controller, in advance.

At the timing of “t₀”, when a signal to be transmitted in generated, themobile station starts transmission of data based on “R₀”,instantaneously.

In addition, at the timing of receiving the AGCH from a radio basestation (t₁, t₂), the mobile station performs transmission of data basedon the transmission rates, which are indicated by the AGCH (R₁, R₂).

Actions and Effects of Transmission Rate Control System According toEmbodiment of the Present Invention

According to the transmission rate control method in accordance with theembodiment of the present invention, in a channel to which atransmission rate control method is applied, it is possible to starttransmission of data instantaneously, to comply with a transmission ratecontrol, and to reduce a delay due to the transmission rate control whendata to be transmitted is generated by notifying, at the radio networkcontroller, at the timing of a call setup and the like, a primaryallowable transmission rate of the EDCH; starting, at the mobilestation, after the call setup, transmission of data below the primaryallowable transmission rate, when a data to be transmitted is generated;and controlling, at the mobile station, the transmission rate of theEDCH based on the Absolute Grant Channel (AGCH) from a radio basestation.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and the representative embodimentsshown and described herein. Accordingly, various modifications may bemade without departing from the scope of the general inventive conceptas defined by the appended claims and their equivalents.

1. A transmission rate control method wherein a mobile station controlsa transmission rate of an uplink channel, based on a scheduling grantsignal notified by a radio base station, in an EUL scheme, comprising:notifying, at a radio network controller, at a timing of a call setup, aprimary allowable transmission rate of the uplink channel to the mobilestation, by a layer-3 message; starting, at the mobile station, whendata to be transmitted is generated after the call setup, transmissionof the data by the uplink channel, at a transmission rate which is equalto or lower than the primary allowable transmission rate; transmitting,at the radio base station, an absolute grant signal as the schedulinggrant signal, to the mobile station, by a layer-2 message; andcontrolling, at the mobile station, the transmission rate of the uplinkchannel, based on the absolute grant signal transmitted from the radiobase station.
 2. A mobile station which controls a transmission rate ofan uplink channel, based on a scheduling grant signal notified by aradio base station, in an EUL scheme, comprising: a first receiving unitconfigured to receive, from a radio network controller, at a timing ofcall setup, a primary allowable transmission rate of the uplink channel,by a layer-3 message; a starting unit configured to start, when data tobe transmitted is generated after the call setup, transmission of thedata by the uplink channel, at a transmission rate which is equal to orlower than the primary allowable transmission rate; a second receivingunit configured to receive an absolute grant signal as the schedulinggrant signal, from the radio base station, by a layer-2 message; and acontrolling unit configured to control the transmission rate of theuplink channel, based on the absolute grant signal transmitted from theradio base station.
 3. A transmission rate control system wherein amobile station controls a transmission rate of an uplink channel, basedon a scheduling grant signal notified by a radio base station, in an EULscheme, comprising: a radio network controller configured to notify, ata timing of a call setup, a primary allowable transmission rate of theuplink channel to the mobile station, by a layer-3 message, and toindicate, to the mobile station, to start, when data to be transmittedis generated after the call setup, transmission of the data by theuplink channel, at a transmission rate which is equal to or lower thanthe primary allowable transmission rate; and a radio base stationconfigured to transmit an absolute grant signal as the scheduling grantsignal, to the mobile station, by a layer-2 message and indicate, to themobile station, controlling, at the mobile station, the transmissionrate of the uplink channel, based on the absolute grant signal.